Add progressive web app companion for cross-platform access

Vite + TypeScript PWA that mirrors the Android app's core features:
- Pre-processed shelter data (build-time UTM33N→WGS84 conversion)
- Leaflet map with shelter markers, user location, and offline tiles
- Canvas compass arrow (ported from DirectionArrowView.kt)
- IndexedDB shelter cache with 7-day staleness check
- Service worker with CacheFirst tiles and precached app shell
- i18n for en, nb, nn (ported from Android strings.xml)
- iOS/Android compass handling with low-pass filter
- Respects user map interaction (no auto-snap on pan/zoom)
- Build revision cache-breaker for reliable SW updates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pwa/node_modules/nanoid/bin/nanoid.cjs

@@ -0,0 +1,55 @@
+#!/usr/bin/env node
+
+let { nanoid, customAlphabet } = require('..')
+
+function print(msg) {
+  process.stdout.write(msg + '\n')
+}
+
+function error(msg) {
+  process.stderr.write(msg + '\n')
+  process.exit(1)
+}
+
+if (process.argv.includes('--help') || process.argv.includes('-h')) {
+  print(`
+  Usage
+    $ nanoid [options]
+
+  Options
+    -s, --size       Generated ID size
+    -a, --alphabet   Alphabet to use
+    -h, --help       Show this help
+
+  Examples
+    $ nanoid --s 15
+    S9sBF77U6sDB8Yg
+
+    $ nanoid --size 10 --alphabet abc
+    bcabababca`)
+  process.exit()
+}
+
+let alphabet, size
+for (let i = 2; i < process.argv.length; i++) {
+  let arg = process.argv[i]
+  if (arg === '--size' || arg === '-s') {
+    size = Number(process.argv[i + 1])
+    i += 1
+    if (Number.isNaN(size) || size <= 0) {
+      error('Size must be positive integer')
+    }
+  } else if (arg === '--alphabet' || arg === '-a') {
+    alphabet = process.argv[i + 1]
+    i += 1
+  } else {
+    error('Unknown argument ' + arg)
+  }
+}
+
+if (alphabet) {
+  let customNanoid = customAlphabet(alphabet, size)
+  print(customNanoid())
+} else {
+  print(nanoid(size))
+}